Error: null is not an object (evaluating 'a.split')

[rcebulko]

This error first surfaced last summer, and has reached the first page of errors in AMP Error Reporting

Error: null is not an object (evaluating 'a.split')
    at split (https://raw.githubusercontent.com/ampproject/amphtml/2004030010070/src/url.js:198)
    at url (https://raw.githubusercontent.com/ampproject/amphtml/2004030010070/src/url.js:222)
    at (https://raw.githubusercontent.com/ampproject/amphtml/2004030010070/extensions/amp-ad-custom/0.1/amp-ad-custom.js:73)
    at (https://raw.githubusercontent.com/ampproject/amphtml/2004030010070/extensions/amp-a4a/0.1/amp-ad-network-base.js:155)

The error occurs when trying to .split a URL string. The source of the URL is a call to AmpAdNetworkBase#getRequestUrl, which gets the URL from its element's src attribute. Below this access, there is a devAssert with the message Invalid network configuration: no request URL specified. When that happens in production, however, there is no handling of a missing request URL.

I suspect the component fails to display anything in this failure case. If I understand correctly and this is a misconfiguration on the part of the publisher, maybe this should be caught and logged as a user error?

/cc @ampproject/wg-ads

[powerivq]

Look like src is not required in the validator. We are making changes on the validator to outlaw it.

[rcebulko]

Closing this because of #27624